Multizone capacitive anti-pinch system

ABSTRACT

An anti-pinch assembly is used for a closure panel supported by the motor vehicle. The closure panel is movable between an open position and a closed position. A controller is operably connected to the closure panel for controlling the operation of the closure panel. A position sensor is connected to the controller for indicating the position of the closure panel as the closure panel moves between the open and closed positions. A capacitive sensor is mounted on the frame of the vehicle and connected to the controller for providing an output signal to the controller indicative of the presence of a foreign object in the path of the closure panel. The controller varies the function of the capacitive sensor through a plurality of threshold levels as a function of the position of the closure panel as indicated by the position indicator. In a critical zone of travel, namely, travel of the closure panel nearing the closed position, the capacitive sensor can be utilized in either a contact mode or a non-contact mode or a combination of both.

FIELD OF THE INVENTION

The invention relates to an anti-pinch system for a closure systemassociated with an aperture of a motor vehicle. More specifically, theinvention relates to an anti-pinch system for an aperture of a motorvehicle wherein the anti-pinch system differentiates a number of zones.

DESCRIPTION OF THE RELATED ART

Motor vehicles typically have anti-pinch systems associated with poweredclosure assemblies used to selectively open and close an aperture. Byway of example only, an aperture of a motor vehicle is found within adoor or side and the closure panel associated therewith is a window andits associated control mechanism. A non-exhaustive list of closureassemblies includes door windows, sliding doors, liftgates, deck-lids,sunroofs and the like.

The anti-pinch systems associated with these closure assembliestypically sense the presence of a foreign object in the path of theclosure panel by using characteristics such as motor current or afeedback device, such as a Hall effect sensor, position sensors,tachometer and the like. These feedback devices sense an abnormalcharacteristic in the parameter being sensed relative to the normal orunobstructed operating characteristic of the closure panel.

U.S. Pat. No. 6,051,945, issued to Furukawa on Apr. 18, 2000, disclosesan anti-pinch assembly for a closure panel. A processor controls a motorthat moves the windowpane between its open and closed positions. A Halleffect sensing device is positioned such that it can sense the velocityof the output shaft of the motor. To measure velocity, the Hall effectsensors are disposed around the shaft of the motor. A magnet is securedto the shaft and provides the magnetic field required sensed by the Halleffect sensors. Once the velocity of the shaft is measured, accelerationis derived and the force is calculated using the mass of the windowpane.This system requires the use of multiple sensors and calculations todetermine the presence of an object.

Simple detection of obstructions based on motor speed or electricalcurrent passing through the motor are inadequate due to the normallyvarying characteristics of these parameters through the full range ofmotion for the closure panel.

SUMMARY OF THE INVENTION

The disadvantages of the prior art may be overcome by providing ananti-pinch assembly that prevents objects from getting caught by aclosure panel of a motor vehicle by providing an anti-pinch systemhaving multiple zones of varying sensitivity.

According to one aspect of the invention, there is provided ananti-pinch assembly is used for a closure panel supported by the motorvehicle. The closure panel is movable between an open position and aclosed position., A controller is operably connected to the closurepanel for controlling the operation of the closure panel. A positionsensor is connected to the controller for indicating the position of theclosure panel as the closure panel moves between the open and closedpositions. A capacitive sensor is mounted on the frame of the vehicleand connected to the controller for providing an output signal to thecontroller indicative of the presence of a foreign object in the path ofthe closure panel. The controller varies the function of the capacitivesensor through a plurality of threshold levels as a function of theposition of the closure panel as indicated by the position indicator. Ina critical zone of travel, namely, travel of the closure panel nearingthe closed position, the capacitive sensor can be utilized in either acontact mode or a non-contact mode or a combination of both.

BRIEF DESCRIPTION OF THE DRAWINGS

Advantages of the invention will be readily appreciated as the samebecomes better understood by reference to the following detaileddescription when considered in connection with the accompanyingdrawings, wherein:

FIG. 1 is a schematic of one embodiment of the invention;

FIG. 2 is a side view of an aperture in a door of a motor vehicleincorporating one embodiment of the invention;

FIG. 3 is a schematic view of the driving circuit for the invention ofFIG. 1;

FIG. 4 is a cross section of a portion of an aperture and a window panedisposed adjacent a graphic representation of zones; and

FIG. 5 is a cross section of graph of an aperture and a windowpaneincorporating adhesive based sensor strips.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the Figures, an anti-pinch assembly is generally indicatedat 10. The anti-pinch assembly 10 is used in conjunction with a closurepanel assembly. The closure panel assembly includes of a closure panel12, defining a leading edge 13, and its operating system, discussedsubsequently. The closure panel 12 travels along a path between open andclosed positions. The anti-pinch assembly 10 prevents the closure panel12 from pinching or crushing an obstruction or object (not shown) thatmay be extending through an aperture 14 of a motor vehicle 16 (bothshown in FIG. 2) when the closure panel 12 nears the closed position. Itshould be appreciated by those skilled in the art that the closure panel12 may be any motorized or automated structure that moves between anopen position and a closed position. By way of example, a non-exhaustivelist of closure panels 12 include windowpanes, doors, liftgates,sunroofs and the like. Apertures include window frames, door openings,sunroof openings and the like. For purposes of simplicity, the remainderof this disclosure will focus on the windowpane and window framecombination.

The anti-pinch assembly 10 includes a controller 18. The controller 18is electrically connected, directly or indirectly, to a power source 20.A conductor 22 graphically represents this connection. The power source20 is preferably the power source 20 for the motor vehicle 16. The powersource 20 may be a battery, a generator or any other electricitygenerating device or combination thereof.

A motor 24 receives electricity through a conductor 26 that, directly orindirectly, operatively extends between the power source 20 and themotor 24. The motor 24 rotates a shaft 28 operatively connected to theclosure panel 12 in a conventional manner. The operative connectiontransforms the rotational energy into mechanical energy. Morespecifically, the electric output of the motor 24 into an opening andclosing movement of the closure panel 12. The motor 24 optionally may beprovided with separate motor controller. Operation of the motor 24 iseffected by the motor controller.

A position sensor 30 is disposed adjacent the motor 24. The positionsensor 30 identifies the position of the shaft 28 of the motor 24 andgenerates a position signal. By identifying the position of the shaft 28upon receipt of the position signal, the controller 18 determines withspecificity the position of the leading edge 13 of the closure panel,i.e., the windowpane 12. As the shaft 28 rotates, the position sensor 30identifies where along the rotation the shaft 28 is as well as how manyrotations the shaft 28 has executed. The degree of accuracy of theposition sensor 30 is a variable that will depend on the specificdesign.

In one embodiment, the position sensor 30 is a Hall effect sensor thatutilizes a single magnet (not shown) that is secured to the shaft 28.The magnet rotates with the shaft 28 and its magnetic field affects theposition sensor 30 as it passes thereby.

In an alternative embodiment, the position sensor is a Hall effectsensor that is secured to a portion of the mechanism (not shown) thatmoves the windowpane between the open and closed positions. The positionsensor 30 could be secured to a drive screw, glass run channel or someother portion of the mechanism that moves proportionally to thewindowpane or closure panel 12.

A capacitive sensor 32 is mounted relative to the window frame in aspaced relation and electrically connected to the controller 18.

The capacitive sensor 32 is capable of determining changes in magneticfields in the surrounding space due to the introduction of an objectthat has a dielectric that is different than that of the surroundingspace. The capacitive sensor 32 can be tuned to detect smaller changesin the surrounding space, i.e., when an object is extending through thewindow frame 40 but not touching the window frame 40, referred to as anon-contact mode. The capacitive sensor 32 detects changes in thesurrounding space defined by the aperture 14 by measuring thecapacitance of the capacitive sensor 32, discussed subsequently. Changesoccur prior to the immediate closing of the closure panel 12 and when anobject extends therethrough. An object extending through the aperture 14will disrupt the dielectric fields being measured by the capacitivesensor 32 and the sensor 32 will responsively generate an output signalrelative thereto.

The capacitive sensor 32 may also be used in a second mode, i.e., acontact mode. In the contact mode, the sensitivity of the capacitivesensor 32 is reduced. Therefore, a change in the dielectric fieldsurrounding the capacitive sensor 32 triggers the anti-pinch assembly 10only when the capacitive sensor 32 is moved by the object when itactually contacts the sensor 32 or the sealing system 37 that houses thesensor 32. The sensitivity of the sensor 32 is reduced so that theleading edge 13 of the closure panel 12 does not trigger the anti-pinchassembly 10, which would result in the closure panel 12 failing to reachits closed position ever.

Referring to FIG. 4, the capacitive sensor 32 is molded into a flexible,and/or low durometer compound, in a range of less than 40-50 Shore. Thecompound is flexible and configured as the sealing system 37 of theaperture 14. Flexibility of the sealing system 37 can also be controlledby the cross-sectional configuration, including controlling thickness ofthe arm and walls supporting the capacitive sensor. In the embodimentshown in FIG. 4, the capacitive sensor 32 is molded directly into thesealing system 37.

Referring to FIG. 5, wherein like primed numerals represent similarelements in an alternative embodiment, the capacitive sensor 32′ may beadded as an aftermarket item by using adhesive 39 to attach thecapacitive sensor 32′ to the sealing system 37′.

Referring to FIG. 2, a door 36 of a motor vehicle 16 is shown. The door36 defines the aperture 14 (a window frame in this case) as an openingextending between a base 38 of the door 36 and around a window frame 40having a forward boundary 42, an upper boundary 44 and a rearwardboundary 46. The capacitive sensor 32 extends along the forward 42 andupper 44 boundaries. The capacitive sensor 32 is designed to measure theelectromagnetic field directly therebelow within the aperture 14.

The capacitive sensor 32 is preferably a long conductor that extends outfrom and along a window frame 40 at a predetermined distance from thewindow frame 40. The predetermined distance creates a specificcapacitance for the capacitive sensor 32 because the capacitive sensor32 uses the window frame 40 as ground. Any changes in the distancebetween the capacitive sensor 32 and the window frame 40 changes thecapacitance in a manner far greater than when an object extends throughthe window frame 40 but does not touch the capacitive sensor 32. Thischange in capacitance is monitored by the controller 18. If an object,regardless of its dielectric constant, contacts the capacitive sensor 32enough to flex it out of its position, the change is detected by thecontroller 18, which will subsequently stop and/or reverse the closureof the window.

The controller 18 includes a threshold generator 33 that generates athreshold value for the capacitive sensor 32. This threshold determinesin which zone the anti-pinch assembly 10 is operating. The threshold isa value of a dielectric that the capacitive sensor 32 can detect. Thethreshold generator 33 includes a pulse generator 34 and a thresholdcapacitor 35. The threshold capacitor 35 is connected in parallel withthe capacitive sensor 32 and is approximately 1000 times the capacitanceof the capacitive sensor 32. The pulse generator 34 generates a regularpulse train of less than 5 volts, preferably 3-5 volts at a frequency ofabout 12 Mhz (200-500 ns per pulse), which signal is applied to thecapacitive sensor 32. Since the capacitive sensor 32 is small incomparison with the threshold capacitor 35, the capacitive sensor 32will become fully charged quickly. Once charged, the pulse train isreflected back to the threshold capacitor 35 thereby charging it in astepped manner, graphically represented at 39, until the thresholdcapacitor 35 is fully charged. A counter 137 counts the number of pulsesrequired to fully charge the threshold capacitor 35 and the count isplaced in a floating memory. The capacitors 32, 35 are then dischargedor reset and the process is re-started.

The count can be averaged over time so that the effects of weather andother extrinsic conditions can be factored out. A comparator 45 comparesthe counts of successive counts.

The determination of the presence of an obstacle is performed bymonitoring the count. A measured signal is generated based on themonitored count. Any obstacle, whether it be a body part or otherwise,extending into the window aperture 14 or contacting the seal 44 willaffect the dielectric constant of the field. The number of pulsesrequired to fully charge the threshold capacitor 35 will increase shouldan object be present, resulting in an increased measured signal. If thechange between a predetermined number of successive counts deviates orincreases beyond a first predetermined threshold signal or count, thecontroller 18 determines that an object has extended through the windowframe 40 or has moved the capacitive sensor 32 by touching or moving thesealing system 37.

When detection of an obstacle is made, the controller 18 then changesthe motor signal being sent to the motor 24. The new motor controlsignal directs the motor 24 to either stop the closure panel 12 frommoving or to reverse the direction in which the shaft 28 is rotating,retracting the closure panel 12. If the closure panel 12 is returned toits open position, the controller 18 normalizes the motor control signaland allows the motor 24 to operate according to normal operation. If theclosure panel 12 remains in the same position, the anti-pinch assembly10 will not allow the closure panel 12 to continue to its closedposition until after the compare value is eliminated.

As noted previously, the motor may be provided with a separate motorcontroller having a position sensor. Thus, the motor controller willprovide a position signal to the controller 18 and the controller 18will send a motor control signal back to the motor controller.

Referring to FIG. 4, a graphic representation of multiple zones isgenerally shown at 56. The graph 56 shows each zone 58, 60, 62 as afunction of position or location of the leading edge 13 of thewindowpane 12. Each different zone 58, 60, 62 is contiguous with thenext such that the leading edge 13 of the windowpane 12 can never in aposition where controller 18 is not monitoring the capacitance of thecapacitive sensor 32. Each of the zones 59, 60, 62 is a graphicrepresentation for each of a plurality of threshold values above whichthe count must reach before the anti-pinch assembly 10 stops or reversesthe windowpane 12.

In the lower or primary zone 58, the controller 18 increases thesensitivity of the capacitive sensor 32 to allow it to detect thepresence of an object even when the object is low enough to avoidphysically moving the capacitive sensor 32.

In the secondary zone 60, usually about 4 mm separating the upper edge13 of the windowpane 12 from the sensor 32, the controller 18 decreasesthe sensitivity of the capacitive sensor 32. The position sensor 30generates the position signal and the controller 18 responsivelydetermines when the windowpane 12 enters the secondary zone 60.

In this zone of operation, the ability to detect an object is reduced.In other words, the controller 18 applies a second predeterminedthreshold that has a magnitude and/or duration greater than the firstpredetermined threshold.

The reduction in sensitivity allows the windowpane 12 to approach thecapacitive sensor 32 without the controller 18 misidentifying thewindowpane 12 as an object that might be pinched between the windowpane12 and the window frame 40. As may be appreciated by those skilled inthe art, a decrease of sensitivity still allows the capacitive sensor 32to detect an object contacting it. Therefore, should an object remain inthe path of the windowpane 12 as the upper edge 13 approaches thesealing system 37, the controller 18 will still be able to detect it andstop or retract the windowpane 12.

In the optional third or upper zone 62 of operation, the controller 18deactivates the capacitive sensor 32. This allows the windowpane 12 toenter the sealing system 37 to properly seal against thereto. Thecapacitive sensor 32 is deactivated because, depending on the sealingsystem 37; the capacitive sensor 32 may move upon entry. If it werestill active, it would inhibit the closing of the window or aperture 14.Upon the windowpane 12 being retracted, the controller 18 reverts to thereduced sensitivity mode (intermediate zone 60) and, subsequently, thehigher sensitivity mode (lower zone 58). The anti-pinch assembly 10 willremain active until the windowpane 12 is returned to its closed positionabutting the sealing system 37.

The invention has been described in an illustrative manner. It is to beunderstood that the terminology, which has been used, is intended to bein the nature of words of description rather than of limitation. Manymodifications and variations of the invention are possible in light ofthe above teachings. Therefore, within the scope of the appended claims,the invention may be practiced other than as specifically described.

1. An anti-pinch assembly for a closure panel of a motor vehicle havinga closure frame and said closure panel is movable between open andclosed positions along a path using a closure motor, said anti-pinchassembly comprising: a controller; a position sensor operably connectedto said controller, said position sensor generating a position signalindicative of a position of the closure panel as the closure panelmoves; and a capacitive sensor mounted on the motor vehicle andpositioned to sense a capacitive field and operably connected to saidcontroller to provide an output signal to said controller, saidcapacitive sensor operative to sense changes in the capacitive fieldresulting from an object extending between the closure frame and theclosure panel and thereafter stops the closure panel from moving towardsthe closed position, wherein said controller operates said capacitivesensor at a plurality of threshold levels providing multiple sensitivitylevels.
 2. An anti-pinch assembly as claimed in claim 1 wherein saidcontroller includes a threshold generator to alter said plurality ofthreshold levels upon changing ambient conditions.
 3. An anti-pinchassembly as claimed in claim 2 wherein said threshold generator includesa threshold capacitor electrically connected to said controller inparallel with said capacitive sensor.
 4. An anti-pinch assembly asclaimed in claim 3 wherein said threshold generator further includes apulse generator for generating a series of electrical pulses and fortransmitting said series of electrical pulses to said capacitive sensorto charge same.
 5. An anti-pinch assembly as claimed in claim 4 whereinsaid threshold generator includes a counter operably connected to saidpulse generator to count each of said series of electrical pulses.
 6. Ananti-pinch assembly as claimed in claim 5 wherein said position sensoris disposed adjacent the closure panel to identify the position of theclosure panel.
 7. An anti-pinch assembly as claimed in claim 5 wheresaid position sensor is disposed adjacent the closure motor.
 8. Ananti-pinch assembly as claimed in claim 7 wherein said position sensoris a Hall effect sensor.
 9. An anti-pinch assembly as claimed in claim 8wherein said capacitive sensor extends along a portion of the closureframe.
 10. An anti-pinch assembly as claimed in claim 9 wherein saidcapacitive sensor is fabricated from an elongated conductor.
 11. Ananti-pinch assembly as claimed in claim 1 wherein said controller variesthe function of the capacitive sensor through a plurality of thresholdlevels as a function of the position of the closure panel as indicatedby the position indicator.
 12. An anti-pinch assembly as claimed inclaim 1 wherein the capacitive sensor operates in a contact mode, anon-contact mode or a combination of both.
 13. An anti-pinch assemblyfor a closure panel of a motor vehicle having a closure frame and saidclosure panel is movable between open and closed positions with respectto the closure frame using a closure motor, said anti-pinch assemblycomprising: a controller; a position sensor disposed adjacent theclosure motor and operably connected to said controller, said positionsensor generating a position signal indicative of a position of theclosure panel as the closure panel moves; and a capacitive sensormounted on the motor vehicle and operably connected to said controllerto provide an output signal to said controller, wherein said controlleroperates said capacitive sensor at a plurality of sensitivity levelsallowing said capacitive sensor to identify a foreign object extendingthrough the closure frame and stops the closure panel from moving towardthe closed position when said capacitive sensor identifies the foreignobject extending through the closure frame.
 14. An anti-pinch assemblyas claimed in claim 13 wherein said position sensor is a Hall effectsensor.
 15. An anti-pinch assembly as claimed in claim 14 wherein saidcontroller includes a threshold generator to alter said plurality ofthreshold levels upon changing ambient conditions.
 16. An anti-pinchassembly as claimed in claim 15 wherein said threshold generatorincludes a threshold capacitor electrically connected to said controllerin parallel with said capacitive sensor.
 17. An anti-pinch assembly asclaimed in claim 16 wherein said threshold generator further includes apulse generator for generating a series of electrical pulses and fortransmitting said series of electrical pulses to said capacitive sensorto charge same.
 18. An anti-pinch assembly as claimed in claim 17wherein said threshold generator includes a counter operably connectedto said pulse generator to count each of said series of electricalpulses.
 19. An anti-pinch assembly as claimed in claim 18 wherein saidcapacitive sensor extends along a portion of the closure frame.
 20. Ananti-pinch assembly as claimed in claim 19 wherein said capacitivesensor is fabricated from an elongated conductor.
 21. A method fordetecting the presence of an obstacle in a path of a closure panelmovable by a motor between an open position and a closed position usinga capacitive sensor, a threshold capacitor and a pulse generator, themethod comprising the steps of: generating a threshold signal; measuringthe dielectric in a field extending in the path of the closure panel togenerate a measured signal; comparing the measured signal with thethreshold signal; and stopping the closure panel from moving towards theclosed position when the measured signal exceeds the threshold signal.22. A method as claimed in claim 21 wherein the step of generating athreshold signal includes the step of producing a pulsed signal.
 23. Amethod as claimed in claim 22 including the step of counting the pulsesin the pulsed signal to create a pulse count.
 24. A method as claimed inclaim 23 including the step of comparing the pulse count to thethreshold signal.
 25. A method as claimed in claim 24 wherein the stepof stopping the closure panel occurs when the pulse count exceeds thethreshold signal.
 26. A method as claimed in claim 25 wherein thethreshold signal includes a plurality of threshold values.
 27. A methodas claimed in claim 26 including the step of using one of the pluralityof threshold values based on the position of the closure panel along itspath.
 28. A method as claimed in claim 27 including the step of usingthe capacitive sensor to generate the measured signal.
 29. A method asclaimed in claim 28 including the step of using the threshold capacitorto generate the threshold signal.